In India, at least 15 people have drowned in the eastern state of Bihar, a disaster management official said, describing it as the worst flood there in 30 years. Adjacent West Bengal state reported another three deaths.

Torrential rains in Nepal's western Gulmi district caused a landslide that smothered seven farm workers.

Snakes driven out of their usual habitat fatally bit nine people in villages in Bangladesh's flooded northern district of Pabna in the last few days, the daily New Age reported, while hospitals across the region have reported a rush of patients with diarrhoea.

Meanwhile, the lives of millions of other people in the subcontinent are simply on hold as they sit on their roofs, high ground or in relief camps, most relying on their governments to bring food, clean water, clothes and medicine.

About 4,000 people waded up with their livestock onto a river dyke in Sirajganj, 150 km (94 miles) north of Dhaka, the Bangladeshi capital. Troops nearby were trying to plug a breached embankment.

Anwar Hossain, 25, said he had been suffering the floods for a week before deciding to evacuate his family.

"Living there became impossible as the Brahmaputra continued to swell, raising the flood level close to the top of my house," he told Reuters, referring to one of more than a dozen rivers in the low-lying country that have burst their banks.

The flooding should subside over the course of the coming week, Bangladesh weather officials said on Sunday.

The seasonal monsoon weather has damaged or destroyed thousands of buildings, drowned swathes of crops, closed schools and offices, blocked roads, disrupted flights and knocked out power and telephone lines.

Around a thousand people have been killed because of the region's torrential rains so far this year, according to official reports, in what is an annual occurrence during the June-September rainy season.